Isotope's second album is a fairly different beast than its predecessor, since half the group is gone, including the main songwriter, keyboardist Brian Miller. In to replace Jeff Clyne is Hugh Hopper fresh from Soft Machine (Boyle and Hopper had met on Yamashta's East Wind group), while the keys are taken by the relative unknown Lawrence Scott, while Boyle and Morris remain pat. Released still in 74 and again on Gull Record, with a stunning headphones artwork, hitting a bit pretentiously at how much of an earful the album is.
Needless to say that the line-up change totally changes the group's sound, definitely tilting the balance in Boyle's favour, newcoming Scott simply not able to fill Miller's shoes right from the bat. Songwriting-wise, Boyle and Hopper take the lion's share, while Scott gets two tracks in, and not exactly the weakest - there are none in this album.

What strikes with Illusion is the way the album is much more Mahavishnu-esque, most noticeable in Spanish Sun, but in the title track, or in short Boyle's songs. Boyle is obviously enamoured with McL's playing and tries to emulate it, and somehow manages it to his own credit and no ridicule, far from it. Hopper's tracks don't necessarily have the Soft machine edge you'd expect, but they do have that little rockier edge (as do Scott's two tracks) over Boyle's. Generally the album has its own red-hot sound, despite Boyle's MO influence, and Hopper's Sliding Dogs and Golden section are absolute corkers that deserves the album highlight. And just past Boyle's acoustic Marin Country Girl, Hopper's Lily Kong offers a last hurrah for Hugh, while Scott closes the album with the MO-influenced Temper Tantrum.

Family's Poli Palmer's is not exactly top notch though, thus stopping this album to get an even higher rating, but make no mistake, this is Isotope's best album with some margin. After Illusion's recording, the group would tour Western Europe, just as it had before it. Then an Ameruican tour came, some reinforcements (De Souza on percussion) brought in, Scott leaving just before financial problems forced Hopper to leave as well, leaving Morris and Boyle to rebuild once more